Multi-component shoulder implant assembly with dual articulating surfaces

ABSTRACT

An implant assembly for re-establishing a glenohumeral joint between scapula and humerus bones. A substantially spherical shaped element is adapted to being mounted a reconditioned glenoid cavity defined in the scapula and exhibits a second convex exterior surface projecting from the bone surface. A receiver component has a base with a first convex bone contacting surface adapted to being mounted to a reconditioned humeral head associated with the humerus, the receiver component exhibiting a second convex exterior surface projecting away from the bone surface and exposing a concave profile exhibiting only a rim edge therebetween at an outer exposed seating end of said second convex surface for supporting the components in inter-articulating fashion.

CROSS-REFERENCE TO RELATED APPLICATIONS

This Application is a Division of application Ser. No. 13/592,738 filedon Aug. 23, 2012. Application Ser. No. 13/592,738 claims the benefit ofU.S. Provisional Application 61/526,388 filed on Aug. 23, 2011.Application 13/592,738 claims the benefit of U.S. ProvisionalApplication 61/526,404 filed on Aug. 23, 2011, the contents of which areincorporated herein in their entirety.

FIELD OF THE INVENTION

The present invention is directed to a shoulder implant assembly and,more specifically, to a multi-component implant assembly incorporating aball and a receiver mounted to first and second shoulder joint definingbones. An optional third substantially spherical shaped and intermediatedefining component establishes dual and spaced apart universal andarticulating surfaces with the fixedly mounted ball and receiverproviding evenly distributed wear profiles for increased useful life ofthe implant, as well as relieving associated ligament tension.

BACKGROUND OF THE INVENTION

The prior art discloses various types of artificial implants, such asreplacing damaged natural joint constructions including those for theshoulder. Examples of these include each of the modular humeral headresurfacing system of Winslow et al., U.S. 2006/0009852 and U.S.2005/0107882, each of which incorporates a two piece humeral componentfor use in joint arthroplasty which is adapted to be implanted into ajoint and engaged by a likewise implanted socket component.

SUMMARY OF THE INVENTION

The present invention discloses an implant assembly for re-establishinga glenohumeral joint between a scapular and humerus. The implantincludes a ball adapted to being mounted to a reconditioned glenoidcavity defined in the scapula. A receiver is adapted to being mounted toa reconditioned humeral head associated with the humerus.

The substantially spherical shaped element is interposed between theball and receiver and establishes first and second articulatingsurfaces. A concave recess is defined in an exposed face of the ball forseating in articulating fashion a portion of the spherical element.

A concave recess is defined in the spherical shaped element for seatingin articulating fashion an exposed portion of the scapula mounted ball.Each of the ball, spherical element and receiver is constructed of analternating material including at least one of a polymer, polymercomposite, metal, metal composite or polymer/metal admixture.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference will now be made to the attached drawings, when read incombination with the following detailed description, wherein likereference numerals refer to like parts throughout the several views, andin which:

FIG. 1 is an assembled view of a yet further mortified shoulder implantassembly exhibiting only first and second scapula and humerus mountedcomponents and eliminating the inter-disposed and supported spheroidshaped component; and

FIG. 2 is an exploded view of the arrangement of FIG. 1 and betterdepicting the inner concavity profile defined in the humerus mountingreceiver and for seating the ball mounted in the scapula; and

FIGS. 3-5 depict a series of supporting Prior Art illustrations of ahuman anatomical shoulder joint, and for which the multi-componentassembly provides an in situ and reconditioned implantation option.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As will be described in additional detail with reference to thesucceeding variants, the present invention discloses a multi-componentshoulder implant assembly for providing an in-situ and reconditionedinstallation option which is an improvement over other conventionaljoint implant installations.

Prior to describing in detail the configuration of the multi-componentshoulder implant depicted in FIGS. 1-2, a Prior Art depiction of ananatomically correct human shoulder is shown in FIGS. 3-5 and whichincludes three bones consisting of the clavicle (collarbone) 1, thescapula (shoulder blade) 2, and the humerus (upper arm bone) 3, as wellas associated muscles, ligaments and tendons (see in particular FIGS. 4and 5). The articulations between the bones of the shoulder collectivelymake up the shoulder joints where the humerus 3 attaches to the scapula2.

An abbreviated and incomplete description of the scapula furtherincludes, at strategic locations a coracoid process 4 and spineconnected acromion 5, in the proximity of which is configured theglenoid cavity 6. The humerus 3 terminates, in relevant part, at anupper end located humeral head 7 (FIG. 4) which generally seats via aninterposed bursa 8 (FIG. 3).

The three joints of the shoulder further include each of theglenohumeral, acromioclavicular and sternoclavicular joints. Theglenohumeral joint, see as identified at 9 in FIG. 5, is the main jointof the shoulder and the generic term “shoulder joint” usually refers tothis ball and socket joint that allows the arm to rotate in a circularfashion or to hinge out and up away from the body.

As is best depicted in the prior art view of FIG. 4, associated types ofjoint cartilage include articular cartilage located on the ends of thebones and which allows the bones to glide and move on each other andlabrum cartilage located in the shoulder. In combination, the shoulderas constructed exhibits sufficient mobile for undertaking a wide rangeof actions of the arms and hands as well as being sufficiently stable asto allow for actions such as lifting, pushing and pulling. Thiscompromise between mobility and stability results in a large number ofshoulder problems not faced by other joints such as the hip.

With reference now to the embodiments of the invention set forth inFIGS. 1-2, and for purposes of ease and clarity of illustration, asimplified depiction is shown of the glenohumeral joint establishedbetween the scapula 2 and humerus 3 and in which all ligaments, musclesand tendons are removed. In each instance, and prior to installation ofthe multi-component implant assembly (such as occurring aftersignificant degradation of the natural glenohumeral joint or in otherinstances in which an accident or other traumatic incident has resultedin significant damage), an initial (in situ) surgical reconditioningprocedure is employed of the opposing joint defining surfacesestablished by the humeral head 7 and the glenoid cavity 6. Thisincludes employing relevant surgical drilling and shaping instruments(also not shown) in order to prepare the joint defining locations of thebones for subsequently attaching selected components associated with theimplant assembly and as will now be described.

The above stated, and referring initially to each of FIGS. 1 and 2, apair of assembled and exploded views, both generally at 10, are depictedof a shoulder implant assembly for installation within reconditioned andopposing end locations of the patient's scapula 2 (represented byreconditioned profile 12) and humerus (further represented byreconditioned profile 14), and as is best shown in the exploded view ofFIG. 2. The implant assembly 10 includes, collectively, a stem supportedand substantially semi-spherical component, also termed a ball elementhaving a main convex surface 16 defining an annular perimeter with areverse convex bone contacting surface 17 which is mounted within thereconditioned recess 12 of the scapula glenoid cavity.

A further receiver component includes a convex bone contacting surface(see at 18), a stem mounting portion 20 projecting from a lower endlocation of the bone contacting surface 18. The receiver componentexhibits a substantially spherical shape with a main convex surface (seeat 21 and which likewise defines an annular or perimeter boundary withthe convex bone contacting surface 18).

A reduced dimension concave profile 22 is configured at an outer exposedseating end of the main convex surface 21 of the receiver component, theconcave profile 22 exhibiting only a rim edge therebetween at an outerexposed seating end of the main convex surface 21 and is sized forseating directly the convex profile of the pseudo spherical ball element16 (see again FIG. 2) in order to define an articulating relationshipbetween the components 16 and 18. As further shown in FIG. 2, an axis 24extending through a center location of the stem mounting portion 20extends at a non collinear angle relative to a further axis 26 extendingthrough the receiver component at a midpoint location of the concaveprofile 22 (such as in particular depicted as a substantially rightangle).

The ball element 16 and receiver component 18 are each constructed ofany suitable material including any type of plastic, metal or admixedcomposite. While not limited to any specific variant, the materialselection for these components can alternate between any suitablematerial (e.g. heavy duty, wear resistant and sanitary polymeric,polymeric composite, surgical steel/aluminum, other metal or metalcomposite, as well as plastic/metal admixture.

The exploded view of FIG. 2 better depicts the configuration of the ballelement 16, such as exhibiting an outwardly semi-spherical or convexexhibiting end face on a surface thereof, and with a reverse extendingstem 28 which seats within a hidden recess configuration (not shown)established within the reconditioned innermost profile 12 of the scapulaglenoid cavity, the stem portion 20 of the receiver component 18 seatingwithin a like configured inner most recess configuration establishedwithin the corresponding humeral head reconditioned profile 14. In atypical surgical procedure, a medical bonding cement or other suitablefastener/adhesive (not shown) is employed for anchoring the ball element16 and receiver component 18 to the respective bone 2 and 3 ends, itbeing further understood that the configuration of these elements iscapable of being reversed (e.g. the ball element 16 mounting to thehumeral head and the receiver component 18 to the scapula glenoidcavity).

Referring again to the existing arrangement of ligaments, tendons andmuscles depicted in the Prior Art views of FIGS. 3-5, these provide theanchoring/seating support for retaining the articulating relationshipsestablished between the ball element 16 and receiver component 18, itfurther being understood that the components are capable of beingretrofit installed within the reconditioned bone ends of the patientwithout the necessity of the ligaments and tendons being severed ofotherwise impacted, thereby enhancing the universal motion profileafforded by the design and likewise reducing recovery time for thepatient. As previously described, the ability to segment thearticulating motion of the gleno-humeral joint into a pair of spacedarticulating surfaces serves to both enhance artificial joint mobilityas well as to more evenly distribute an associated wear profile of thejoint, thereby increasing expected life of the assembly.

Having now described our invention, other and additional preferredembodiments will become evident to those skilled in the art to which itpertains, and without deviating from the scope of the appended claims.

We claim:
 1. An implant assembly for re-establishing a glenohumeraljoint between a scapula and humerus, comprising: a pseudo-sphericalelement having a base with a first convex bone contacting surface, saidbase terminating in a stem portion extending therefrom such that thebase is adapted to mount to a reconditioned glenoid cavity defined inthe scapula, said element exhibiting a second convex exterior surfaceprojecting from the bone surface; a receiver component having a basewith a first convex bone contacting surface adapted to being mounted toa reconditioned humeral head associated with the humerus, said receivercomponent exhibiting a second convex exterior surface projecting awayfrom the bone surface and exposing a concave profile exhibiting only arim edge therebetween at an outer exposed seating end of said secondconvex surface, said second convex exterior surface of saidpseudo-spherical shaped element articulating relative to said concaveprofile, a first axis extending through a central location of saidconcave profile defining a non collinear angle relative to a second axisextending through a centerline of said stem portion of said receivercomponent.
 2. The implant assembly as described in claim 1, each of saidpseudo-spherical shaped element and receiver component being constructedof at least one of a polymer, polymer composite, metal, metal compositeor polymer/metal admixture.
 3. The implant assembly as described inclaim 1, said first and second axes defining as substantially rightangle.